After finding the mode, I would launch 3 Metropolis-Hasting algorithm chains
Normally, I found that Dynare will lauch these three MH Markov Chains on-by-one basis.
I mean that after finishing the first MH Markov Chain, then the second one will be lauched, so on and so forth
So I would ask that whether Dynare can lauch all 3 MH Markov Chains at the same them (paralell basic)? If such, please instruct me

Dear Prof. @jpfeifer
Thank you so much for your instruction. I hava another question
What is consequence for my estimation if I lauch the MH agorithm in two cases
First case: lauching the MH Markov chains at the same time (paralell)
Second case: lauching the MH Markov chains one-by-one basis
Is this affected my estimation?
Thank you so much for that

Usually there is no difference between the two approaches. A slight difference may occur if your clients are different machines/operating systems. In this case the random numbers used may be different. But if your MCMC has properly converged, the random numbers do not matter anymore.